So I just 100%'d the Krypt (got the achievement) without getting the four secret money chests (which is a lame prize btw). So I guess that means other secrets could exist, right?
It's rumored to be 10 total secrets but no findings as of yet. Only 4 secrets were found so 6 are still unknown and not even confirmed really for that matter.... We'll wait and see though. Once there's more confirmed secrets and info on how to unlock those then I'll post them in the OP. ^-^